3b^2-12=16 need help

Solve for b:
3 b^2-12 = 16

Add 12 to both sides:
3 b^2 = 28

Divide both sides by 3:
b^2 = 28/3

Take the square root of both sides:
Answer: |   b = 2 sqrt(7/3)         or        b = -2 sqrt(7/3)